1. Field of the Invention
The present invention relates to a light-emitting device, and more particularly, to an organic light-emitting device.
2. Discussion of Related Art
An organic light-emitting device (OLED) such as an organic light-emitting diode is a light-emitting device using a light-emitting phenomenon due to electron-hole recombination generated in an organic light-emitting layer. The OLED can be operated at relatively low voltage of about 1 to 10V and made thin. The OLED provides unchangeable picture quality even when viewed from a location other than the front due to a wider viewing angle than a liquid crystal display (LCD), and does not leave an afterimage due to faster response speed than the LCD. In addition, it is possible to form the OLED on a flexible substrate, and thereby to implement a flexible display and a flexible electronic apparatus. However, the OLED may require a switching device such as thin film transistor for switching since it is not self-switched, and thereby switching speed may decrease. Further, since an additional process for forming the switching device is required, the manufacturing cost may increase.
To solve those problems, an organic light-emitting transistor (OLET) has been suggested. In the OLET, holes and electrons may each move according to a direction of an electric field and emit light due to recombination in the organic light-emitting layer. However, since the hole mobility is greater than the electron mobility, the recombination may occur not at the center between the electrodes but near an electron injection electrode. In this way, when the recombination occurs near the electron injection electrode, light-emitting efficiency may decrease since non-radiative recombination is predominant.
In addition, each layer is generally formed by a deposition method such as chemical vapor deposition (CVD), sputtering, evaporation, etc. in the OLET. However, such a method of forming the OLET requires that each process be performed in a vacuum chamber, and therefore cost may increase.